1. Field of the Invention
The present invention relates to new dentifrice cleaning and polishing agents and to the formulation and utilization of dentifrice preparations incorporating such cleaning and polishing agents. In particular, the invention relates to a dentifrice cleaning and polishing composition comprising calcined kaolin in combination with talc and preferably titanium dioxide.
Incorporation of talc into a calcined kaolin based dentifrice permits the rheological properties of the dentifrice to be significantly improved. The provision of a talc modifier also enhances the polishing ability of calcined kaolins, improves fluoride and stannous ion availability and reduces abrasion. Moreover, the addition of titanium dioxide permits these advantages to be achieved without sacrificing the desired whiteness of the dentifrice.
The compositions of this invention serve to clean and polish dental hard tissue in a novel manner such that reaccumulations of pellicle and materia alba and occurrence and reformation of plaque and calculus on oral hard tissue are markedly reduced, thereby significantly reducing the occurrence of gingivitis and other soft tissue and periodontal disease. Fluoride-containing anticariogenic adjuvants such as sodium fluoride, stannous fluoride, and, especially, 1:2 molar mixtures thereof, may also usefully be incorporated in such compositions.
2. Description of the Prior Art
Dental research has developed substantial evidence that beyond the age of thirty-five years loss of teeth is predominantly the result of periodontal involvement rather than dental caries. However, evidence in the literature suggests that gingivitis itself may be present in a large portion of the population at a much earlier age. In this form the disease is reversible. A major factor contributing to periodontal disease is the accumulation of certain forms of dental plaque and calculus (e.g., salivary tartar) on the teeth. These accumulations result in tissue inflammation of the surrounding gingiva, and, as the condition increases in severity, the peridontal fibers and supporting bone subsequently become affected. These reactions lead to the destruction of the supporting structures and the subsequent mass loss, in most instances, of sound teeth.
Heretofore, commercially available dentifrices containing abrasives such as insoluble sodium metaphosphate (NaPO.sub.3), calcium hydrogen phosphate dihydrate/anhydrous calcium hydrogen phosphate, (CaHPO.sub.4.2H.sub.2 O/CaHPO.sub.4), calcium pyrophosphate (Ca.sub.2 P.sub.2 O.sub.7), and silica (SiO.sub.2) have exhibited relatively unsatisfactory enamel-polishing qualities and consequently have not been wholly effective in preventing the reaccumulation of materia alba, oral debris, plaque, pellicle, exogenous stains, and dental calculus. In particular, while conventional cleaning and polishing agents used with a toothbrush are capable, to varying degrees, of removing materia alba, food particles, exogenous stains, and other tooth surface pigmentations when utilized in ordinary daily brushings, they have not exhibited the ability to remove the more resistant forms of enamel pigments and to produce a smooth tooth surface resistant to dental plaque and calculus formation. Furthermore, these conventional abrasives leave the teeth esthetically less desirable than would more effective polishing agents.
The beneficial effects, in terms of a reduction in the incidence of dental caries, resulting from the incorporation of water-soluble fluoride salts are well known. However, efforts to utilize such salts in dentifrices suitable for home use have been handicapped by the tendency for fluoride ions to be deactivated and rendered unavailable by other ingredients, particularly the abrasive component of such dentifrices. While generally speaking, dentifrice abrasives in therapeutic products used today are to varying degrees compatible with fluoride agents, there is a wide variation in compatibility. Calcium-containing abrasives are not particularly compatible. While the non-calcium-containing abrasives are somewhat more compatible, they frequently are inferior with regard to enamel polishing.
Saul et al., U.S. Pat. No. 3,105,013 recommends using calcined aluminum silicate as a dental abrasive on the basis of its compatibility with fluoride adjuvants. However, the preferred material of Saul et al. is commercially available under the trademark "Kaopolite SF". Kaopolite SF is off-white in color and is thus esthetically undesirable in a commercial dentifrice.
Japanese Pat. No. 24224/74 describes dental abrasives combining calcined kaolins with other abrasives such as calcium carbonate, calcium hydrogen phosphate dihydrate, and the like.
Applicants' U.S. Pat. No. 4,122,163 describes dentifrices formulated with highly purified calcined kaolin particles from which titanium impurities have been excluded. The patent also describes replacement of the kaolin with other dental abrasive materials including talc, but it does not recognize that the rheological properties of calcined kaolin may be improved thereby or the kaolin need not be specially purified in order to be successfully employed, nor does it disclose that the overall performance of the abrasive can in fact be improved.
The prior art calcined kaolin dentifrices have all encountered formulation problems due to the dilatancy of the material when provided in paste form. In addition, they encounter shelf life problems when used with certain anticariogenic additives.
Thus, prior art materials intended for use as cleaning and polishing constituents of dentifrice preparations have not been entirely satisfactory in one or more of the following respects: relatively poor cleaning and polishing performances (especially with respect to prevention of reaccumulation of dental calculus, pellicle, materia alba, and the more resistant forms of oral hard tissue stains and pigmentations); incompatibility with fluoride and stannous ion-containing anticariogenic agents; adverse abrasion; difficult, expensive manufacturing requirements; and rinsing and rheological problems.